Embrapa articulates plan to combat ripe grape rot in São Paulo vineyards

Grape producers in the Circuito das Frutas Paulista – an area that encompasses ten municipalities in São Paulo with emphasis on fruit growing – are losing their production due to the spread of ripe grape rot, a disease caused by the fungus Glomerella cingulata. The fungus found favorable environmental conditions to multiply in the region's vineyards and, for at least four years, it has been harming local winemakers. In this last harvest, however, the damage caused by the pathogen reached an unprecedented level, with losses ranging from 30% to 100% of the harvest.

“This is not an unknown disease, but the way it happened this year, it scared a lot of people. Some producers even ripped out the entire vineyard, thinking they could no longer control it in a viable way”, says Renê Tomasetto, president of the Jundiaí Agricultural Association. He believes that the climatic factor favored the multiplication of the fungus in the region and highlights that 2023 was an atypical year, marked by above-average rainfall, with rainfall during the pruning and harvesting season, interspersed with dry periods. With ideal humidity and temperatures, the fungus advanced aggressively, winning the battle to stop its spread.

At the Grape and Wine Sector Chamber of the State of São Paulo, the Jundiaí Agricultural Association presented to Embrapa a demand for measures to reduce the pressure of the disease and, if possible, eradicate Glomerella in the region's vineyards. With representation in this Chamber, Embrapa Territorial (SP) coordinated the participation of researchers from Embrapa Uva e Vinho (RS) and state agencies. With experts from city halls and local agricultural entities, this technical team drew up an Emergency Plan to Control Ripe Grape Rot to help wine growers in São Paulo.

The disease

caused by fungus Glomerella cingulata, ripe grape rot causes circular reddish-brown spots on the fruit, which later affect the entire bunch, leaving the grape dark and withered. Temperatures between 25 °C and 30 °C and high humidity from rain, dew, irrigation or fog are ideal conditions for sporulation, dissemination, infection and development of the disease.

Control practices

Embrapa analyst Rafael Mingoti worked directly at this stage. He assesses that, from the union of institutions, adjustments can be made to disease control practices, from winter treatments, fertilization, cultural treatments and biological and chemical controls, which in itself will bring beneficial results.

The first phase of the Plan consists of selecting producers receptive to the installation of ripe grape rot control trials. From the 1st to the 4th of July, the group of experts visited some properties located in the municipalities of Jundiaí, Louveira, Itatiba, Itupeva, Jarinu, Indaiatuba and Elias Fausto, to talk to the owners about the project and collect cultural remains – samples in the in which the pathogen survives during the dormant period of plants, such as mummified bunches (attacked in the last harvest), rachis and buds from vine branches.

This material will be taken to the Phytopathology Laboratory at Embrapa Uva e Vinho, where the next stage will be developed, aimed at isolating the pathogen, identifying it through morphology and testing to detect the presence of isolates resistant to certain groups of fungicides. “It is necessary to identify the species of the asexual phase of Glomerella and evaluate their sensitivity and tolerance to fungicides, as some isolates can, in addition, become resistant to certain products due to indiscriminate use”, explains the researcher Lucas Garrido, one of the experts from Embrapa Uva e Vinho invited to this action, with the researcher Rosemeire Naves (both in the photo above).

The scientist highlights that the set of proposed actions foresees two lines of confrontation: the first, with measures for immediate adoption, aims to reduce the pressure of the pathogen present in the vineyards; and second, the reduction in the disease rate throughout the harvest. “It is important to work in at least two harvests to reap results. At first, some vineyards will be visited to mitigate the causes that contributed to the disease epidemic in the region and correct some practices adopted by producers. Then, in the medium term, comes the adoption of the best products and practices, which will be studied throughout these two harvests, in such a way that it becomes a routine protocol”, reinforces Garrido.

The group of experts will also install tests on selected properties and monitor the results. Garrido adds that this work will investigate the effectiveness of the products being tested to accelerate the decomposition of crop residues from the vineyard – materials in which the pathogen survives from one harvest to the next. They will also apply resistance inducers, increasing the plant's defense capacity; in addition to developing integrated management recommendations for producers who suffered large losses.

The knowledge generated by these experiments will be transferred to Circuito das Frutas producers in events to be organized. “Carrying out experiments in the field and in the laboratory will result in a great benefit, which is the certainty of what species the fungus is and which biological and chemical measures and products are most effective for its control. All of this will restore producers’ confidence in the practices and management of farming”, says Mingoti.

Impacts inside the gate

The municipality from which the most shocking reports come is Elias Fausto, located around 130 km from the capital of São Paulo. There, the disease compromised entire production, filling families with hopelessness and making them abandon their work in the fields in search of other means of survival.

Atalivio Rufino has owned a farm in the city for 16 years. He says that 90% of the grapes were compromised by Glomerella in production at the beginning of the year. The little that remained was sold, but he was unable to balance the family's finances and, therefore, had to give up an employee who helped them. Despite the bleak scenario, he decided not to give up and will fight again against ripe grape rot. He intends to use the reserves to invest in other control measures. “We got a little bit of fat from previous sales and because of that we are able to get by”, he says. The Atalivio property is one of 13 selected for the proposed tests.

In the municipality of Itatiba, there is the property of Antônio Mingotte. Living with grapevines since his childhood, he says he was scared by the scale of Glomerella's spread this year. “A spread of the disease like this year, I have never seen in my life! We need to control this disease soon, otherwise we won’t be able to produce,” he declares. Currently with more than 12 thousand grape trees, he says that he harvested the fruits from a block (plot) and realized that they were all rotting. “I couldn’t afford to send it to the market. I ripped it off and threw everything into the bush,” he said.

Impact beyond the gate

23 km from Itatiba is Jundiaí, known as the Land of Grapes. A grape variety characteristic of the region originated in the city's soil: Niagara Rosada. Recently, the fruit received the Geographical Indication certificate, which opened doors to expand its market beyond the state of São Paulo, reaching neighboring places, such as Rio de Janeiro and Paraná, and even further away, such as Distrito Federal, Goiás , Pernambuco and Ceará.

Grapes are the flagship of local agribusiness. It promotes the Grape Festival, which has attracted thousands of tourists to the city for 90 years between January and February, boosting business in the region. It is also linked to rural tourism. Five tourist routes include visits to table and wine grape properties in Jundiaí. On the Wine Route, for example, winemakers open their properties to visitors and sell the wine produced on site. “Today there are already 20 wineries authorized by the municipality to receive these tourists. The disease affects the entire tourism chain in the city”, comments Eduardo Alvarez, manager of the Agribusiness, Supply and Tourism Unit.

Many producers, he highlights, obtain their income from the harvest and pay activity: when the planted fruits are harvested by tourists. “If the rot persists for another harvest, this would affect the chain as a whole, as the basis of tourism in Jundiaí is agriculture”, he says.

One of the most affected winegrowers in the city is Ademir Minjoni. He reports that he used to harvest 40 tons of grapes per hectare, but, since 2022, Glomerella has been devastating his grape fields, causing gradual losses that now reach 90%.

This has a direct impact on your pocket. The money from the sale of the grapes paid production costs and generated income for investment in the property. “This year I will not invest in the site. I even thought about sowing tomatoes to see if I can pay the bills in the meantime, but I can't buy fertilizer; a friend gave it to me. If it continues the way it is, I'll have to stop. A lot of people are stopping. Jundiaí is known as the Land of Grapes. Will the grapes run out?” he says.

Good habits

A few kilometers away, there is an example that could be a source of encouragement for Mr. Minjoni (in front, in the photo above). Anderson Tomazetto leads a property where the soil has been cultivated for more than 100 years. He says he saw the first symptoms of ripe grape rot on his land four years ago, but at the time, he didn't feel any major damage. “In the past, some rotten grains would appear. But, in 2022, it came with force and I ended up losing 15 tons of grapes”, he recalls. Seeking technical guidance from Embrapa, he changed his management and achieved good results.

“I started taking the branch, the infected bunches, and even sick grapes I put in a separate bucket and took them outside the court. I also applied sulfocaustic syrup when the harvest ended. It is a sequence of treatments associated with management practices. If you don’t do both together, it won’t produce results,” she teaches. Tomazetto considers combating the fungus to be the winegrower’s biggest challenge. “The fungus is something we don’t see, and by the time we notice it, the plant is already contaminated,” he says.